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Transesophageal echocardiography (TEE) is the gold standard to exclude the diagnosis of left atrial appendage thrombus (LAAT) in patients with nonvalvular atrial fibrillation (AF) prior to cardioversion. Using transthoracic echocardiography (TTE), Ayirala et al (JASE 2011) demonstrated that a ratio of left ventricular ejection fraction (LVEF) to the left atrial volume index (LAVI) > 1.5 rules out LAAT with 100% negative predictive value. We sought to validate this prediction tool in an external patient cohort.
We conducted a retrospective cohort study of consecutive patients with AF who underwent TEE to “rule-out” LAAT prior to cardioversion who had TTE in the prior 1 year. In all subjects, the LAVI was measured and the LVEF was calculated using Teichholz formula. The LVEF/LAVI was calculated. Per the original paper, we considered a ratio < 1.5 as “test (+)” and ≥ 1.5 as “test (−)” in predicting LAAT. The γ2 was used to compare dichotomous variables and the Student's T-test was used to compare continuous variables.
A total of 215 pts were analyzed, among whom 19 (8.8%) had LAAT by TEE. Patients with LAAT had higher mean CHADS2 score (2.5 vs 1.9, P 0.04), lower mean LVEF [(24 (±13) vs 44 (±20), P <0.001], higher mean LAVI [44 (±13) vs 30 (±13) ml/m2, P < 0.001] and higher prevalence of heart failure (79% vs 52%, P 0.02). Multivariate logistic regression identified LAVI and LVEF as independent predictors of LAAT (LAVI: OR 1.054, CI 1.016–1.093, P 0.005 – LVEF: OR 0.948, CI 0.915–0.983, P 0.004). All 19 (100%) subjects with LAAT had LVEF/LAVI < 1.5 vs 87 (44%) of those without LAAT, P <0.001. The ROC curve analysis demonstrated that the LVEF/LAVI ratio has excellent discriminatory capacity to diagnose LAAT with an area under the curve of 0.83 (CI 0.77-0.90, P < 0.001). The sensitivity and specificity of LVEF/LAVI < 1.5 were 100% and 55.6%, respectively. The negative and positive predictive values were 100% and 17.9%, respectively.
This investigation validates a simple TTE prediction rule to exclude the diagnosis of LAAT. Application of this tool can potentially spare > 50% of the AF patients from undergoing pre-cardioversion TEE, which has tremendous economic implications.
Poster Sessions, Expo North
Sunday, March 10, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Imaging: Echo: Atrial Imaging
Abstract Category: 18. Imaging: Echo
Presentation Number: 1226-339
- 2013 American College of Cardiology Foundation